ORGANIC
LETTERS
2006
Vol. 8, No. 20
4585-4587
Gold-Catalyzed Efficient Formation of
Alkenyl Enol Esters/Carbonates from
Trimethylsilylmethyl-Substituted
Propargyl Esters/Carbonates
Shaozhong Wang and Liming Zhang*
Department of Chemistry, UniVersity of NeVada, Reno, NeVada 89557
Received July 23, 2006
ABSTRACT
A gold-catalyzed efficient method for the preparation of alkenyl enol esters/carbonates is developed. Besides the mild reaction conditions and
high catalytic efficiency, the excellent E-selectivity of the nonenolic double bond is remarkable.
Alkenyl enol esters/carbonates are versatile synthons in
organic synthesis, readily engaging in a range of transforma-
tions including regioselective Diels-Alder reactions,1 ste-
reoselective hydrogenation into chiral allylic esters,2 and Pd-
catalyzed enantioselective allylation.3 They are generally
prepared from the corresponding enones at elevated tem-
peratures4 or under strong basic or acidic conditions, thus
raising the issue of functional group compatibility.
alkenes8 has led to a rapid increase of Au-catalyzed prepara-
tive methods for various synthetic intermediates. In our
continuing effort in discovering synthetic potentials of
propargylic esters in the presence of a Au catalyst,9 we
discovered and herein reported an efficient preparative
method of alkenyl enol esters/carbonates from trimethyl-
silylmethyl-substituted propargylic esters/carbonates. More-
over, high E-selectivities are observed in the nonenolic C-C
double bond of the products.
Recent revelation of the exceptional capability of Au salts/
complexes5 in the activation of alkynes,6 allenes,7 and
(6) For recent selected examples, see: (a) Kang, J.-E.; Shin, S. Synlett
2006, 717-720. (b) Yao, X.; Li, C.-J. Org. Lett. 2006, 8, 1953-1955. (c)
Ferrer, C.; Echavarren, A. M. Angew. Chem., Int. Ed. 2006, 45, 1105-
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9340-9341.
(7) (a) Zhang, Z.; Liu, C.; Kinder, R. E.; Han, X.; Qian, H.; Widenhoefer,
R. A. J. Am. Chem. Soc. 2006, 128, 9066-9073. (b) Nishina, N.; Yamamoto,
Y. Angew. Chem., Int. Ed. 2006, 45, 3314-3317. (c) Morita, N.; Krause,
N. Angew. Chem., Int. Ed. 2006, 45, 1897. (d) Sromek, A. W.; Rubina,
M.; Gevorgyan, V. J. Am. Chem. Soc. 2005, 127, 10500. (e) Hoffmann-
Roeder, A.; Krause, N. Org. Lett. 2001, 3, 2537. (f) Hoffmann-Roeder, A.;
Krause, N. Org. Lett. 2001, 3, 2537. (g) Hashmi, A. S. K.; Schwarz, L.;
Choi, J.-H.; Frost, T. M. Angew. Chem., Int. Ed. 2000, 39, 2285. (h)
Hoffmann-Roeder, A.; Krause, N. Org. Lett. 2001, 3, 2537.
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Chem. Soc. 1976, 98, 1967. (b) Potman, P. R.; van Kleef, F. J.; Scheeren,
H. W. J. Org. Chem. 1985, 50, 1955. (c) Hansen, D. W.; Pappo, R.; Garland,
R. B. J. Org. Chem. 1988, 53, 4244.
(2) Boaz, N. W. Tetrahedron Lett. 1998, 39, 5505.
(3) (a) Behenna, D. C.; Stoltz, B. M. J. Am. Chem. Soc. 2004, 126, 15044.
(b) Trost, B. M.; Xu, J. J. Am. Chem. Soc. 2005, 127, 17180.
(4) Kalita, B.; Bezbarua, M. S.; Barua, N. C. Synth. Commun. 2002, 32,
3181.
(5) For reviews, see: (a) Ma, S.; Yu, S.; Gu, Z. Angew. Chem., Int. Ed.
2006, 45, 200. (b) Hashmi, A. S. K. Angew. Chem., Int. Ed. 2005, 44, 6990.
(c) Hoffmann-Roder, A.; Krause, N. Org. Biomol. Chem. 2005, 3, 387. (d)
Arcadi, A.; Di Giuseppe, S. Curr. Org. Chem. 2004, 8, 795. (e) Arcadi,
A.; Di Giuseppe, S.; Marinelli, F.; Rossi, E. AdV. Synth. Catal. 2001, 343,
443. (f) Echavarren, A. M.; Nevado, C. Chem. Soc. ReV. 2004, 33, 431. (g)
Hashmi, A. S. K. Gold Bull. 2003, 36, 3. (h) Dyker, G. Angew. Chem., Int.
Ed. 2000, 39, 4237.
(8) (a) Yang, C. G.; He, C. J. Am. Chem. Soc. 2005, 127, 6696. (b)
Yao, X. Q.; Li, C. J. J. Am. Chem. Soc. 2004, 126, 6884.
(9) (a) Wang, S.; Zhang, L. J. Am. Chem. Soc. 2006, 128, 8414. (b)
Zhang, L.; Wang, S. J. Am. Chem. Soc. 2006, 128, 1442. (c) Zhang, L. J.
Am. Chem. Soc. 2005, 127, 16804.
10.1021/ol0618151 CCC: $33.50
© 2006 American Chemical Society
Published on Web 09/06/2006